The present invention relates to a profiling or forming arrangement with a profiling or forming machine and with a welding device in its processing path for manufacturing a shaped workpiece formed from a sheet-metal strip, the roll forming machine exhibiting roll tools positioned one behind the other in the feeding direction of the workpiece and the roll tools being formed in each case essentially by at least two driven or freely rotating forming rollers positioned on parallel axes.
Many different types of such profiling arrangements are known and serve in forming and manufacturing a wide range of shaped workpieces, especially hollow shaped workpieces or tubes.
From DE 198 34 400 C1, a profiling arrangement with a welding device for manufacturing tubes of this type in which the initially opposing edges of the workpiece are bent toward each other and then joined together with the aid of the welding device is known. Behind the welding device in the feeding direction, additional tools are usually present for aligning and calibrating the welded workpiece.
In the case of workpiece cross-sections deviating from a tubular cross-section, it is known to form overlapping areas of the edges of the workpiece and to join these together through joint stamping. The stiffness of such shaped workpieces does not meet all requirements. It has therefore already been known to join overlapping areas on such roller-shaped workpieces through folds, which is complicated and also makes necessary additional consumption of material in the area of the fold. Such a shaped workpiece also exhibits greater weight.
The present invention is therefore aimed at providing a profiling arrangement of the type mentioned above with which shaped workpieces of greater strength or stiffness can be produced, whereby sheet material of reduced thickness can be employed without considerably increasing machine costs.
In solving this seemingly contradictory problem, the above-mentioned profiling installation with a roll forming machine and a welding device is characterized by the fact that the welding device exhibits a single energy source which is connected to at least two welding heads for producing at least two weld joints on the workpiece.
In this way, shaped workpieces formed from practically endless sheet material can be provided and stabilized with two weld joints without requiring two separate correspondingly expensive and mechanically complicated welding devices. By applying two weld joints to a roller-shaped workpiece, for example, a hollow shaped workpiece with crosspiece, a considerable improvement in the stiffness of this workpiece is obtained, and overlapping areas for producing folds are simultaneously avoided so that material can also be saved in this way. Nevertheless, machine costs are kept within limits because only a single welding device is required.
The welding heads can be arranged in their operating position to act on spaced and/or directly opposing contact points of the workpiece in the area of its feed path. In this way, the workpiece is guided past these welding heads as a result of feeding especially by the roll form tools and is provided there with the desired weld joints.
Here, in the area of each of the welding heads at least one supporting roller is provided which supports or guides the workpiece in the area of the welding head and prevents swerving or deflection from the welding head. Correspondingly precise weldjoints can be developed at the intended points.
A refinement of the present invention of very considerable importance can be provided in that the welding apparatus includes a laser-beam source or a high-frequency generator and in the fact that the energy delivered thereby is divided and can be fed to the individual welding heads. In this way, one can especially well realize the idea of supplying and operating at least two welding heads using only a single energy source for the welding device, i.e., applying at least two weld joints to a roller-shaped workpiece for appropriate stabilization thereof using only a single energy source. For example, a hollow shaped workpiece with crosspiece can be formed in this way and can be welded at both cross-sectional ends of the crosspiece, which provides a two-chamber hollow shaped workpiece of great stiffness.
It is especially favorable if the welding device includes a laser-beam source and has prisms and/or mirrors for splitting the laser beam and guiding it to the laser welding heads. The welding energy can thus be optically split upon use of a laser welding device, which also makes possible a correspondingly simple guiding to the welding heads independent of their arrangement.
The partial beams developing as a result of splitting the laser beam coming from the laser-beam source can also be conducted at least partially via light guides.
In this way, a welding device with a laser-beam source proves to be especially suitable for realizing the present invention.
The welding device exhibiting a high-frequency generator can include at least two oscillating circuits for dividing the high-frequency energy, which can be fed to welding heads designed as sliding contacts. In this way, the welding device can also be operated via high frequency.
The profiling installation provided with a welding device having a laser-beam source can be appropriately developed in the direction that interrupters are provided in the individual laser-beam paths for simultaneous or chronologically offset interruption of each of the partial laser beams in producing stitched weld joints. In many cases, it can namely suffice to produce stitched weld joints, i.e., not uninterrupted continuous weld joints, but rather, only sectioned weldjoints. Beyond this, the possibility of interrupting the weldjoint also permits, interrupting the feeding of the finished workpiece in order, for example, to cut it into specific lengths.
The welding energy can be adapted to different feeding rates of the workpiece in the sense that the welding heads can be supplied with less welding energy during slow feeding, for example, in a phase of acceleration of the workpiece, with more energy during subsequent feeding at maximum speed, and again with less energy during reduction of the feeding speed down to stoppage and in the sense that the supply of welding energy can be turned off or is turned off just before or upon coming to a stop.
While continuous processing takes place during normal operation with constant feeding, a discontinuous course of operation with alternating feeding and stopping can be carried out due to this possibility for adapting the current welding energy to different feeding rates. As already mentioned, the stopping can be utilized, for example, for cutting off a certain portion of the finished workpiece, the profiling arrangement then usually includes a cutting or separating mechanism behind the welding device and appropriately also behind the calibrating or straightening device.
Saving of energy during the welding process can be attained especially during processing of relatively thick workpieces through the fact that the roll forming machine includes coining rolls for coining material attenuations in the workpiece in the area of the subsequent weld joint or weld joints. Due to this coining, the point to be welded then has a shorter cross-sectional dimension compared to the actual material thickness so that correspondingly less welding energy suffices for welding and/or a greater feeding and welding speed can be selected.
Depending on the shape of the workpiece to be formed and multiply welded, the welding heads operated especially with partial laser beams can be arranged on both sides of the shaped workpiece produced by the roll forming machine and can thus act in opposing directions and face each other or they can be offset in the feeding direction or with respect to height and/or they can be adjustable in these different positions. The splitting up of the welding energy, especially a laser beam, thus permits an especially appropriate adaptation of the welding heads to the most widely varying shapes of the workpiece to be produced. For example, a double-T profile can be formed which exhibits an overlapping of sheet metal and a weld joint in the area of its central segment under each of the two crosspieces. However, the crosspieces, which can be formed here of a double layer of bent sheet metal, can also in turn exhibit a hollow cross-section in order to attain appropriate stiffness in several directions.
The welding heads can be positioned according to the side on which the overlapping to a connecting segment is appropriate.
A further possibility for saving welding energy and/or increasing the feeding speed of the workpiece can be provided in that the welding heads can be moved in the feeding direction of the workpiece and can be moved back again after a predetermined or adjustable distance, the speed of movement of the welding heads in the feeding direction being less than the feeding speed of the workpiece. In this way, a portion of a weldjoint can be produced with less energy at the welding head in each case in line with the movement of the welding head even though a correspondingly stable weldjoint can be produced since the effective period in this area of the weld is correspondingly longer due to the movement of the welding head with the workpiece in the feeding direction. Here, for example, two welding heads can be alternately active and returnable so that always the welding head moving in the feeding direction produces a weld joint. However, they can also be simultaneously first moved in the feeding direction and then back again, for example, in forming two stitched weldjoints. The lengthened effective time on the workpiece as a result of the accompanying movement of the welding heads can also be utilized in increasing the feeding speed of the workpiece.
Especially upon combination of a few or several of the above-described features and measures, a profiling arrangement is obtained with a roll forming machine and a welding device with which longitudinally welded workpieces or tubes can be provided with two or more weld joints which can be designed as a stitched joint or as a continuous joint. Since the welding energy produced in the welding device is split up, a considerable saving of weight and costs is possible in that, in spite of possible material savings, a greater stiffness and torsional strength of the shaped workpiece to be produced can be attained through the introduction of multiple weld joints. Nevertheless, there is practically no additional expense for equipment compared to a profiling installation with one welding device.